2020 is no longer the future.

Taken from upstream:
https://github.com/hughsie/appstream-glib/commit/953c8e529d7291e60a95e580967ed79ce2c9ccf0

diff --git a/data/tests/broken.appdata.xml b/data/tests/broken.appdata.xml
index f7a5386e..cf80f5b4 100644
--- a/data/tests/broken.appdata.xml
+++ b/data/tests/broken.appdata.xml
@@ -40,7 +40,7 @@
         <p>This is a duplicate release on the same day!</p>
       </description>
     </release>
-    <release date="2020-01-01" version="0.6.2">
+    <release date="2050-01-01" version="0.6.2">
       <description>
         <p>This is a release in the future!</p>
       </description>
diff --git a/libappstream-glib/as-app-validate.c b/libappstream-glib/as-app-validate.c
index c1103ace..f50e4e41 100644
--- a/libappstream-glib/as-app-validate.c
+++ b/libappstream-glib/as-app-validate.c
@@ -864,7 +864,7 @@ as_app_validate_release (AsApp *app,
 				     AS_PROBLEM_KIND_ATTRIBUTE_MISSING,
 				     "<release> has no timestamp");
 	}
-	if (timestamp > 20120101 && timestamp < 20251231) {
+	if (timestamp > 20120101 && timestamp < 20351231) {
 		ai_app_validate_add (helper,
 				     AS_PROBLEM_KIND_ATTRIBUTE_INVALID,
 				     "<release> timestamp should be a UNIX time");
